How can the buyer confirm the receipt and pay more quickly after receiving the goods?

As a buyer, I feel that sometimes I can't pay immediately because I can't get online and other reasons.

Maybe you can send a text message to remind you, but it costs a lot of phone bills a month?

Or you can get a discount if you pay in advance, such as a 10% discount on the day of receipt and a 9.5% discount on two days.